A medical treatment device for treating a patent foramen ovale (hereinafter, referred to as a PFO) has been described in International Publication No. WO2007/100067, the contents of which are hereby incorporated by reference. A PFO is a cardiogenic factor of a stroke and a migraine headache.
The PFO closing device described in International Publication No. WO2007/100067 includes an apparatus which is inserted into the foramen ovale from the right atrium toward the left atrium. A foramen ovale valve is pulled so as to close the foramen ovale, the foramen ovale valve and the atrial septum secundum are sandwiched by a pair of electrodes, and the biological tissue can then be fused by applying electric energy from both the electrodes.
In this device, clamping means are used in which one side thereof is made of a sticking member composed of a needle electrode and the other side thereof is made of a sandwiching member for sandwiching the foramen ovale valve and the atrial septum secundum with respect to the sticking member. The sticking member pierces (i.e., is stuck into) the foramen ovale valve and thereafter, the foramen ovale valve and the atrial septum secundum are sandwiched with respect to the sandwich member, which is the other electrode. Electric energy is applied to the biological tissue and fusion is thereby carried out.
This device can also be used in the case of closing defects such as a congenital atrial septum secundum defect (ASD), a ventricular septal defect (VSD) and a patent ductus arteriosus (PDA). The device has a high general versatility and in particular, foreign substances are not indwelled in the body. The construction of such a device is relatively simple, the procedure is easily performed, and the foramen ovale valve and the atrial septum secundum can be reliably fused.
However, when applying electric energy to the clamping means (in other words, to the electrode) which is exposed to blood, thrombi may easily attach to the clamping means. As such, it is not desirable for electric energy to be carelessly or needlessly applied to the electrodes for fusing the biological tissue.